The Hebrew inscription reads:
Here is buried an old man, sated of years;
[who] all his days went in the ways ...
Mr. Joseph ben Chaim Schw(...)
passed away in good name on Thursday 17th
Kislev and buried on the morrow, on the eve of Shabbat, the 18th inst. in the year 5588 [Dec 7, 1827] And his days were 89 years.

The tombstone is headed "Hevrat Meshivat Nefesh". This was a "Society for the Relief of the Aged Needy of the Jewish Faith" established by the Ashkenazim of London in 1779.